Astrophyllite

Astrophyllite is a rare, needle-like silicate mineral group. Its name comes from the Greek words "aster" meaning star and "phyllon" meaning leaf, referring to its common star-like or radiating crystal habit. It is typically found in pegmatites and hydrothermal veins within granite and other silica-rich igneous rocks. Astrophyllite crystals are often acicular, forming radiating aggregates or fan-shaped sprays.

The mineral's color is usually a metallic golden bronze to brown, though it can sometimes be silvery or iridescent. Its luster is metallic. Astrophyllite is known for its distinctive radiating patterns, which can be quite striking when observed in hand specimens or thin sections. It is relatively soft, with a Mohs hardness of 2.5 to 3, and has a brittle tenacity. Its specific gravity ranges from 3.1 to 3.4.

Chemically, astrophyllite is a complex potassium, iron, magnesium, titanium, manganese, and niobium silicate. It belongs to the astrophyllite group of minerals, which includes several related species with variations in their chemical composition, particularly regarding the amounts of iron and manganese. Due to its rarity and unique appearance, astrophyllite is primarily of interest to mineral collectors and geologists. It is not used in any significant industrial applications. Notable occurrences include locations in Russia, Norway, Canada, and the United States.